Runoff, Soil, and Dissolved Nutrient Losses from No‐Till Soybean with Winter Cover Crops

Abstract

Abstract Soils are more vulnerable to erosion following cropping to soybean ( Glycine max [L.] Merr.) than corn ( Zea mays L.). This has been attributed to lower dry matter production, less residue cover, and soil‐loosening action by soybean roots. To augment soil cover, common chickweed ( Stellaria media L.), Canada bluegrass ( Poa compressa L.), and downy brome ( Bromus tectorum L.) were grown as winter cover crops with no‐till soybean on natural rainfall erosion plots located on a poorly drained Mexico claypan soil (Udollic Ochraqualf). No‐till soybean without a cover crop served as the check. Winter cover crops significantly increased soil cover by 30 to 50% during the critical erosion period of late spring to early summer. Compared to the check, mean annual soil losses from the chickweed, downy brome, and Canada bluegrass were decreased by 87, 95, and 96%, and runoff was reduced 44, 53, and 45%, respectively. Dissolved NH + 4 concentration in runoff from cover crops was 1.61 to 3.72 times more, and dissolved PO 3‐ 4 was 1.61 to 2.86 times more than that of the check. However, runoff from the check plots had 96 to 117% greater concentration of dissolved NO ‐ 3 than cover crop plots. Mean annual dissolved nutrient losses were decreased 7 to 77% by using winter cover crops. Thus, winter cover crops were very effective in reducing soil erosion and dissolved nutrient losses from no‐till soybean.